WP8.1 push mail option not available

[WPCentral Question]

I just updated to cyan on lumia 1520. However many of my email set up don't have the option of "As items arrive", aka push mail settings. Even my default microsoft account doesn't have it. One of my LIVE and Outlook email has this option but the rest don't. Neither does Gmail support push.

Any idea?

Also, even if it has the "As Item Arrive" option, the menu item is at the top of the list, while I saw others have it as the last row of the list.